A change of government has left the Ministry of Justice without a short-term goal for reducing serious crime rates, politicians have been told.

But officials at the ministry and Corrections are backing a move to longer-term targets.

Under questioning from parliament's justice select committee on Thursday, ministry chief Andrew Bridgman said the department no longer had a specific reduction target for the next 12 months.

The previous government set a goal of 10,000 fewer serious crimes a year by 2021, but that was scrapped in favour of a 15-year goal to reduce the prison population by 30 per cent by the new administration.

"It's early days and what we're doing is briefing our minister on how they can achieve that ... That will obviously have an effect on the number of violent crimes as well," Mr Bridgman said.

"There's a huge overlap in that ... the 30 per cent will result in thousands of violent offenders not being in the system."

He told reporters afterwards he expected specific targets would be set after further discussions with the new minister.

Taking questions from the same committee, Corrections chief Ray Smith said the department also no longer had a short-term reoffending reduction target.

"They may well come ... I'm quite certain there will be some sub-targets but they haven't emerged yet," he said.

"(The reduction targets) did drive ... a massive cultural change in how we are and who we and what we are thinking about and do every day, and that's been incredibly positive.

"But the idea that somehow Corrections alone could achieve a reduction in reoffending isn't realistic."

He applauded the move to the 15-year goal.

"I think that gives us a sensible time horizon," he told media.

"What you don't want to do is get into a bunch of short-term measures to undermine long-term success."

Police Commissioner Mike Bush last week told a select committee police had continued to aim for the 2021 goal.